Fuel for gas generating and dispensing systems



hold and commercial uses.

Patented Aug. 24, 1943 FUEL FOR GAS GENERATING AND DISPENSING SYSTEMSLoyd J. White, San Antonio, Tex, assignor Southern Steel Company, SanAntonio, Tex,

a corporation of Texas No Drawing. Application December 6, 1941, SerialNo. 421,994

2, Claims. (01. 4 -52) This invention relates to hydrocarbon fuel foruse inordinary liquefied gas-dispensing systems, such as those designedfor dispensing butane or mixtures of butane and propane which arecomposed predominately of butane. The main idea is to provide a newcommercial fuel, including propane as the main volatile constituent, totake the place of butane and butane-propane blends, now commonly used inunderground systems of the general type disclosed in Patents No. 2,121,-675 and 2,176,829. A further aim is to provide such .-a fuel having arange of vapor pressures comparable to that of butane or commercialbutane-propane blends. A further aim is to provide a new propane fuelcomprising a mixture of propane and normally liquid hydrocarbon fuelwhich may be proportioned and blended so that its vapor pressure, atmaximum operating temperatures, will not exceed the safe, designpressure limits of the many thousands of relatively low pressure, butanestorage and dispensing systems already permanently installed for house-A still further aim is to employ a commercial, normally liquid fuel inmaking the blended mixture which will serve not only to enrich the BTUcontent of the propane vapor, due to its own vapor pressure, but, also,which can easily be separated from the mixture as the propane componentis vaporized in a twostage, pressure reducing, liquid eduction system ofthe type shown in my copending application Ser. No. 420,566, filedNovember 26, 1941.

Other aims and advantages of the invention will appear in theaccompanying specification.

The present National Defense Program contemplates the use of butane ingreatly increased quantities for the manufacture of high octane aviationfuel. 150,000 underground butane gas storage and dispensing systems inuse which would be seriouslyaflected by a curtailment of its use,especially, for cooking, heating and refrigerationv in ruralcommunities. Propane is readily available for such 'uses. However,ordinary commercial propane has a much higher vapor pressure than butaneor butane-propane mixtures composed predominately of butane, and cannotsafely be used in the present low pressure butane systems. For example,at 100 F., propane has a vapor pressure 'of approximately 172 pounds,gauge; while butane, develops a vapor pressure of only 37.5 pounds,gauge, and a mixture of 70% butane and propane-a blend commonlyuseddevelops a vaporpressure of approximately 78 pounds, gauge. Thus, itwill be apparent At present, there are more than that the handling ofpropane requires storage containers and truck tanks of materials havingmore than 100% greater strength and weight than those designed forbutane and butane-propane blends. 7 invention to provide a mixturewherein propane is the main volatile component, which can be stored andtransported in existing low pressure butane containers and which isusable in such systems without requiring expensive alterations, so'thatall butanes (normal butane and iso-butane) may be released as needed formaking high octane, aviation fuel without great inconvenience to thepresent butane gas consumers.

In accordance with this invention, ordinary liquefied propane is mixedwith a normally liquid, hydrocarbon fuel, such as commercial crackedgasoline, benzine, naphtha, or kerosene, or any .readily miscible,normally liquid, petroleum or coal tar distillate which will reduce thevapor pressure of the mixture to within the safe pressure working limitsof existing butane gas systems, most of which systems are-designed andconstructed to safely carry a maximum of 125 pounds, gauge pressure, persquare inch. The

normally liquid fuel is mixed with the propane in such proportion as toreduce its vapor pressure, at 100 F., to within the design workingpressure of the containers to be served, as well as the transporting andstorage equipment. In other words, the vapor pressure of the mixtureshould not exceed, say, 125 pounds per square inch, gauge, at F.However, the-pressure may be much lower, consistent with a desirableminimum of the normally liquid fuel in the mix ture. It is preferred tomix'ordinary gasoline with the propane, because the gasoline componentof the mixture can readily be separated in the system after the mixtureis delivered to a vaporizer and His recoverable for subsequent use valueand improving its flame characteristics.

The ratios of the propane and gasoline will range between, say, '70parts, by volume, of propane to 30'parts of gasoline and 30 parts ofpropane to '70 parts of gasoline, depending on the desired vaporpressures forthe low pressure systems and the range of operatingtemperatures. Forexample, it has been found that an approximately 50-50mixture, byvolume, is highly satis- It is-therefore an'object of thispane mixtures.

- moisture.

It has been found that the new fuelmixture factory, because its vaporpressure, at 100 F., is

between 70 and 80 pounds, gauge, depending upon the volatility of thefuels. Therefore, it comes within the pressure range of gas systemsdesigned forbutane and ordinary butane-pro- The more gasoline added tothe mixture, the less will be its vapor pressure, and

vice versa. There is some moisture present in most-all commercialhydrocarbon fuels and it is highly objectionable in liquefied gassystems, because, in cold temperatures, it may freeze and form ice onthe regulator valve parts, causing them to stick and cease to function.Even though the present fuel mixture has anti-freeze properties,'

it is desirable to add some other anti-freeze solution to it to reducethe freezing point of the moistures in the mixture. For that purpose, asmall quantity of methyl alcohol, say, about one quart to each hundredgallons of the mixture, may be added, because it has an affinity for thesure to deliver some of its own vapor to be mixed with the propanevapor, increasing it.- heat value and, to some extent, improving theflame characteristics of the propane vapor. It is contemplated, however,that many other miscible, normally liquid, hydrocarbon: fuels may beused to advantage and it is to be distinctly understood that the claimsherein are not limited to a propane-gasoline mixture.

It will be understood that commercial propane usually contains other,more, or less volatile constituents, including a small percentage ofethane and some butane. Its composition is known to vary. Therefore, theterm is used in the claims as applying to the commercial product. Theinvention contemplates .any fuel mixture in which propane is thepredominant, volatile component. Y

Obyiously, the invention is not restricted to the particular fuelmixture herein described.

What is claimed is:

1. Asa-fuel for liquefied gas dispensing systems, a mixture of propaneand gasoline consisting of between 70 parts propane, by volume, to 30parts gasoline and 30 parts propane to 70 parts gasoline.

